Mask-cleaning machine



Dec. 4, 1956 H. szczEPANsK 2,772,683

MASK-CLEANING MACHINE Filed July 18, 1952 3 Sheets-Sheal io Mm Ma x "/Z. mm

Dec. 4, 1956 Filed July 18, 1952 H. SZCZEPANSKI 2,772,683

MASK-CLEANING MACHINE SSheets-Sheet 2 /nven for Harry Szczepansk/ AffomeDec. 4, 1956 H. SZCZEPANSKI 2,772,683

MASK-CLEANING MACHINE Filed July 18, 1.952 3 Sheets-Sheet 5 f PRESSUREPRESSURE 5/ :l5 0 REGULATOR GAUGE PRESSURE 49 REGULATOR fi TIMER G FOOT65 VALVE SPRAYING TANK 3-WAY CHECK VALVE VALVE FLUI D TANK 62 lnvemorHarry $zczepanski -ya A,

' Affornex United States Patent MASK-CLEANING MACHINE Harry Szczepauski,Grand Rapids, Mich.

Application July 18, 1952, Serial No. 299,540

4 Claims. (Cl. 134-44) The present invention provides a mask-cleaningmachine for use in conjunction with spray painting equipment. Quantityproduction painting of intricate designs is done with the aid of ashield having cut-out areas corresponding to the areas to be painted onthe products. The mask and product are placed in proper relationship,and a spray nozzle is directed at the opposite side of the mask from theobject to be painted. With this arrangement, the only portions of theobject receiving paint will be those opposite the open areas in themask. Many instances occur in which a portion of the mask is completelysurrounded by a cutaway part, and becomes an island requiring structuralsupport from the adjacent areas. To avoid interfering with the passageof paint, these areas are conventionally supported by bridging. Thisstructure is usually in the form of wire displaced a substantial amountfrom the plane of the mask. With the bridging displaced in this fashion,it is possible to work around the obstruction presented by it, and thusassure that an adequate and uniform layer of paint is applied to theproduct. During the use of these masks, a layer of paint progressivelybuilds up on the bridging and around the edges of the cutaway areas to apoint where the shape of the clear area is distorted. As the paintaccumulates on the bridging, it becomes increasingly difiicult to assurethat the-re are no areas on the painted surfaces that have been blockedoff by the presence of the enlarged bridging. The greater the thicknessof the bridging, the more attention must be given to displacement of theguns to spray on either side of it, or the more dispersion of spray fromadjacent nozzles is required.

Due to the problems resulting from the build-up of paint on the maskstructure, it is conventional practice to periodically clean themthrough exposing them to solvents of various descriptions. Theparticular solvent used will of course be selected for the type of paintbeing handled by the spraying operation, but solvents apparently have arather uniform characteristic of being highly inflammable. Several typesof machines are known to the prior art involving the exposure of masksto a spray of solvent, the spray being motivated by a system of pumpsdriven by electric motors. The presence of electrical wiring, motors,switches, and similar equipment in a machine utilizing highlyinflammable solutions presents a considerable fire hazard; The attentionthat must be given to such mechanical and electrical installations tominimize the fire hazard considerably increases the cost of the unit inthe first instance, and also the maintenance of it in a safe condition.It must also be notedthat the possibility of failure of an electricalsystem is never completely eliminated, even though great precautions aretaken. As long as it is necessary to operate highly inflammable solventsin the presence of electrical systems, a substantial fire hazard ispresent. This situation is generally recognized by insuranceunderwriters.

The present inventionprovides a machine for cleaning masks in whichthere are no electrical systems involved,

2,772,683 Patented Dec. 4, 1956 and in which there is a minimum ofmechanical equipment of any description. The force utilized by thepresent invention to motivate the sprays and the other Workingcomponents is derived from compressed air. The majority of factories andother locations where high production spray painting is performed arealready equipped with compressed air, for it must be utilized in checkvalve in the drain, and an arrangement for supplying air pressure overthe surface of the liquid in the container so as to drive the solventthrough the conduit and to the sprays. After the period of applicationof air pressure is over, the pressure is released and the solutiondrains down back into the container and is ready for another cycle ofoperation.

This invention provides a reciprocating mask-supporting rack, and anarrangement for automatically controlling a spraying cycle which beginsafter the rack has reached its fully inserted position. An arrangementis also provided by the present invention for purging the machine of aparticular solvent that may have previously been in use. With thepurging system, it is possible to use the solventmoving system in such afashion that the entire solution content of the machine is dischargedthrough a hose which may be placed in communication with some otherconta-iner.

The several features of the present invention will be discussed indetail through an analysis of. the embodiments illustrated in theaccompanying drawings. In these drawlngs:

Figure 1 presents a front elevation of one modification of a machineembodying the present invention, with a portion of the housing brokenaway to show the interior construction.

Figure 2 presents a section on the plane 2-2 of Figure 1, andconstitutes a sectional elevation taken from the side.

Figure 3 shows a section taken on the plane 3-3 of Figure 1.

Figure 4 presents a schematic diagram of the relationship of thecomponents of the embodiment of the present invention illustrated inFigures 1-3.

Figure 5 presents a section taken on the plane 55 of Figure 2, on anenlarged scale.

Figure 6- shows an'enlarged illustration of the self-moving nozzlesutilized in the machine illustrated in the previous views.

Referring to Figure 1, a series of masks 10 is shown supported on avertically-reciprocating rack 11 mounted upon aset of rods 12 slideablymounted in bearings 13. The bearings 13 are mounted on a plate 14secured to the housing 15 of the machine. The piston rod 16 isvertically reciprocated by an air cylinder 17, and is connected to therack rods 12 by the end fitting 18.

A spray chamber is defined within the machine by the inner wall 19, thebottom 20, and on the other sides by the walls of the housing 15 and thecover 21. The construction of the cover 21 and the housing 15 at thepoint where these components come together is indicated at Figure 5. Itis preferable that horizontal flanges 22 and 23 upon the cover andhousing respectively also be provided with vertical flanges 24 and 25,with the flange 24 on the cover extending to a point below the. lowerext-remity of the corresponding flange upon the housing. Thisarrangementinhibits any tendency of spray from the central area withinthe chamber to work its way out between the cover and housing. It isalso very preferable to provide an insert 26 of non-ferrous material(preferably brass) to inhibit any tendency to generate a spark as toolsor other equipment are brought in contact with the cover or housingduring periods in which the cover is open.

A central opening 27 in the cover 21 provides for the insertion of themasks within the spray chamber as the rack 11 moves downwardly under theaction of the air cylinder 17. In the modification shown in Figures 1and 2, a seal 28 is provided on the rack 11 to close off any possibleopenings between the rack 11 and the top 21 after the rack is in thefully down position. After the rack has reached this position, sets ofspray heads 29 and 30 on opposite sides of the chamber begin to pro jectsolvent at the masks 10 under the action of equipment to be discussedhereinafter. After the spraying cycle has been completed, the solventaccumulates at the bottom of the chamber and returns to the tank orcontainer 31 via the conduit 32. A check valve 33 prevents any passageof liquid or air in a direction opposite to the arrow 34. If desired,the spray chamber may be ventilated by the application of suction to theconduit 35 communicating with the housing at the manifold 36 through thelouvers 37.

The particular spray head used in the machine illustrated in Figures 1and 2 is illustrated in detail in Figure 6. The spray head systems 29and 30 are mounted upon the conduit-s 38 and 39, respectively, and eachcontain a length of flexible conduit as indicated at 41) in Figure 6. Anozzle 41 of conventional design is positioned at the outer extremity ofthe flexible conduit 40, and the reaction at this nozzle from thepropulsion of the spray tends to make the head position somewhatunstable. As the axis of spray deviates from a straight line, a tendencyis established for the spray head to move laterally and bend the conduit40. This lateral movement usually results in reversing the relativeposition of the spray axis and the inner end of the flexible conduit 40,and produces a random oscillating movement. The flexible conduit 40 canbe satisfactorily constructed from a section of suitable rubber tubing43 reinforced by a helical wire spring 44.

Referring to Figure 4, a schematic diagram is presented illustrating therelationship between the components of the machine. An air inlet locatedat any convenient part of the machine supplies compressed air to theconduit 45. A conduit 46 supplies air to the lower portion of the aircylinder 17 via the pressure regulator 47. Another conduit 48 suppliesair through the pressure regulator 49 to the timing unit 50, a pressuregauge 51 being associated with the pressure regulator to indicate thepressure established thereby. A foot valve 52 communicates with the mainair line via the conduit 53, and also communicates with the timer 50through the conduit 54. The timer 50 supplies compressed air to theconduit 55 for a predetermined duration of time established by thesetting of the adjusting screw 56 in response to actuation of the footvalve 52, the duration of the foot valve actuation being of noimportance. The setting of the pressure regulator 49 is such that higherpressure is supplied to the conduit 55 and to the upper end of the aircylinder 17 through the conduit 57 than is supplied to the lower end ofthe air cylinder 17 by the conduit 46. Consequently, actuation of thefoot valve 52 immediately creates a higher pressure above the pistonthan below, and causes the piston rod 16 to move downwardly. Therack-actuated valve 58 blocks the conduit 59 until the rack 11 is in.its fully down position and inserted in the spray chamber, at whichtime the air pressure of the conduit 55 is supplied to the tank 31through the conduit 59. Referring back to Figure l for a moment, thevalve 58 (not shown in Figure 1) is operated by the actuator 61associated with the air 4 cylinder 17 As the end fitting 18 reaches thefully down position, the actuator 61 is contacted and is urged in adownward direction. Such movement opens the valve 58. The valve 58 maybe of any conventional form.

Application of pressure to the tank 31 causes the solvent containedtherein to move through the conduit 62 through the valve 63 normallythrough the conduit 64 to the spray heads within the chamber indicatedat 65. The valve 63 may also be set for removing from the machine all ofthe solvent contained within the fluid tank 31 by a proper setting ofthe valve. Such an arrangement directs the fluid from the conduit 62through the discharge conduit 66 normally positioned with its dischargeend 67 supported upon a suitable bracket 68 within the chamber 65. Thepurpose of this arrangement is to prevent accidental misplacement of thevalve 63 from resulting in discharging the contents of the tank 31 outon the floor surrounding the machine. When it is desired to dischargethe contents of the tank 31, the flexible conduit 66 is withdrawn fromits position in the tank and directed into another container.

On completion of the duration of the surge of compressed air establishedby the timer 50, the pressure to the fluid tank ceases. Due to theconventional construction within the timer 50, a valve 71 establishes aline of exhaust from the fluid tank back through the check valve 70 andthe conduit 69 through the timer 50, and from there either into theatmosphere through a vent 42 or through a suitable conduit into theinterior of the spraying chamber. The latter arrangement is preferableif a ventilation system similar to that shown in Figure 2 is utilized.The presence of the check valve 70 prevents application of pressure tothe tank before the operation of the rack-actuated valve 58.

The particular details of the present invention illustrated in theaccompanying drawings and discussed herein are for illustrative purposesonly and are not to be considered as a limitation upon the scope of theappended claims. In these claims, it is my intention to claim the entireinvention disclosed herein except as I am limited by the prior art.

I claim:

1. A mask-cleaning machine, comprising: means forming a spray chamber;rack means for supporting masks in said spray chamber; spray meansdisposed within said chamber to direct spray at masks supported by saidrack means; a solvent container disposed below said chamber; drain meansconnecting the bottom of said chamber with said container, said drainmeans including a one-way valve preventing flow from said container;conduit means connecting said container with said spray means to supplysolvent thereto; air-pressure supply means including control means andadapted to apply pressure to said container to induce flow of solvent tosaid spray means, said airpressure supply means including air releasevalve means, timing means actuating said air release valve means toexhaust the air pressure from said container on completion of asolvent-spraying action; and purging means including selector valvemeans in the conduit means connecting said container with said spraymeans and adapted to divert flow therefrom, said purging means includingan extensible discharge conduit connected to said selector valve means,the end of said discharge conduit being normally disposed within saidspray chamber for discharge thereinto and extendable therefrom fordischarge externally of said chamber.

2. A mask-cleaning machine, comprising: means forming a spray chamber;rack means for supporting masks in said spray chamber; spray meansdisposed within said chamber to direct spray at'masks supported by saidrack means; a solvent container disposed below said chamber; drain meansconnecting the bottom of said chamber with said container, said drainmeans including a one-way valve preventing flow from said container;conduit means connecting said container with said spray means to supplysolvent thereto; air-pressure supply means including control means andadapted to apply pressure to said container to induce flow of solvent tosaid spray means, said airpressure supply means including air releasevalve means, timing means actuating said air release valve means toexhaust the air pressure from said container on completion of asolvent-spraying action; and purging means including selector valvemeans communicating with said container, said purging means including anextensible discharge conduit connected to said selector valve means theend of said discharge conduit being normally disposed within said spraychamber for discharge thereinto and extendable therefrom for dischargeexternally of said chamber.

3. A mask-cleaning machine, comprising: means forming a spray chamberhaving an opening in the top thereof; rack means for supporting masks insaid spray chamber, said rack means having a portion adapted to closesaid opening; rack-withdrawing means adapted to withdraw said rack meanstogether with supported masks from said spray chamber through saidopening, said rack-withdrawing mean including a member secured to saidrack and slideably mounted with respect to said spray chamber, and alsoincluding air cylinder means provided with piston means and adapted toreciprocate said member; spray means disposed within said chamber todirect spray at masks supported by said rack means; a solvent containerdisposed below said chamber; drain means connecting the bottom of saidchamber with said container, said drain means including a one-way valvepreventing flow from said container; conduit means connecting saidcontainer with said spray means to supply solvent thereto; firstair-pressure supply means, said first air-pressure supply meansincluding control means and adapted to apply pressure to said aircylinder means to position said rack in said chamber and to saidcontainer to induce flow of solvent to said spray means, saidair-pressure supply means including air release means adapted to exhaustthe air pressure from said container and from said air cylinder on theside of said piston appropriate to induce inward movement of said rackmeans on completion of a solvent-spraying action; rack-actuated valvemeans preventing flow of air to said container until said rack portionhas substantially closed said opening; one-way by-pass air exhaust meansaround said rack-actuated valve means; and biasing means urging saidpiston in a direction to withdraw said rack, said biasing meansincluding second I 4. A mask-cleaning machine, comprising: means forminga spray chamber having an opening; rack means for supporting masks insaid spray chamber, said rack means having a portion adapted to closesaid opening; rackwithdrawing means adapted to withdraw said rack meanstogether with supported masks from said spray chamber through saidopening, said rack-withdrawing means including a member secured to saidrack and slideably mounted with respect to said spray chamber, and alsoin cluding air cylinder means provided with piston means and adapted toreciprocate said member; spray means disposed within said chamber todirect spray at masks supported by said rack means; a solvent containerdisposed below said chamber; drain means connecting the bottom of saidchamber with said container, said drain means including a one-way valvepreventing flow from said container; conduit means connecting saidcontainer with said spray means to supply solvent thereto; airpressuresupply means including control means and adapted to apply pressure tosaid air cylinder means to position said rack in said chamber and tosaid container to induce fiow of solvent to said spray means, said airpressure supply means including air release means adapted to exhaust theair pressure from said container and from said air cylinder on the sideof said piston means appropriate to induce inward movement of said rackmeans on completion of a solvent-spraying action; rack-actuated valvemeans preventing flow of air to said container until said rack portionhas substantially closed said opening; one-way by-pass air exhaust meansaround said rackactuated valve means; and biasing means urging saidpiston in a direction to Withdraw said rack, said biasing means beingadapted to apply forces less in magnitude than those applied by airpressure to induce inward movement of said rack.

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